Bring the water and salt to boil in a medium saucepan . When water is boiling, stir in pinch saffron . Add the rice, reduce heat, cover, and simmer until rice is just tender (about 20 minutes). Meanwhile, in a large bowl, blend vinegar and mustard with a fork. Pour in olive oil in a thin stream, whisking with fork to emulsify. Stir in the peas, bell peppers, parsley, and oregano . When rice is cooked, add it to the bowl and stir well to distribute dressing and ingredients. Let rice cool to room temperature and serve. Or refrigerate up to 1 day, then serve.